Previous studies have shown that carbohydrate supplementation during endurance exercise delays fatigue. While exogenous glucose maintains blood glucose levels in later exercise, it causes reactive hypoglycemia at the start of exercise. In contrast, fructose is not oxidized as efficiently by the muscles nor does it elicit the typoglycemic effect. For these reasons, the purpose of this study is to determine a concentration of glucose-fructose beverage which maintains blood glucose levels throughout exercise, thereby delaying fatigue in endurance exercise.